In medical diagnosis employing an x-ray photographic apparatus, it is necessary to obtain visible images of an affected part of a patient under examination by passing x-rays through that part at a given angle and then to record them as x-ray photographs, for checking the condition of the disease, assessing the effect of the treatment, or deciding the treatment to be adopted. For this purpose, x-ray photographs have heretofore been obtained by causing x-ray radiation to be transmitted through an affected portion of a patient under examination, permitting the resultant x-ray image to directly fall on a film, and developing it. According to another conventional method, an x-ray image that is derived by passing x-ray radiation through an affected part of a patient to be examined is focused onto an image intensifier, for example. The image produced by the intensifier is photographed with a television camera to form a corresponding visible image on a television monitor, for seeing through the affected part. Then, the dosage is changed to a value appropriate for photographing, and an x-ray photograph is taken from the image displayed on the monitor using a camera.
However, where x-ray photographs of an object under examination are directly taken from the transmitted x-rays using a film, a large quantity of dosage is needed to expose the film, increasing the amount of x-ray radiation that leaks away. Hence, the exposure dose of the patient undergoing examination is high. Also, when the apparatus is not remotely controlled, the exposure dose of the operator of the apparatus is high. When images on a television monitor are photographed by a camera as described above, the obtained photographs do not exhibit clear gradations and, therefore, it is impossible to obtain distinct photographs.